Tissue engineered heart valves (TEHV) are produced by seeding cells on a heart valve shaped scaffold material, followed by a culturing period in a bioreactor system. During culture, the cells will produce an extracellular matrix (ECM).
So far no solutions are available to control heart valve geometry during culture. Contractile cells that are being used will compact the new-formed tissue in all possible directions of constrain. Any predefined scaffold geometry at the start of culture will therefore be lost during culture, resulting in an entirely different geometry after culture compared to the imposed starter geometry.
There are two ways of culturing the TEHV. The first method is to culture the TEHVs in a so-called “open configuration”. This means that the individual heart valve leaflets are separated from each other during culture. The benefit of this approach is that the TEHV leaflets do not have to be separated after culture. The problem with this approach is that because cells will build up tension during culture, they will retract the leaflets, which results in shorted leaflets. In addition, because of the internal tension that builds up in the leaflets, the initially curved shape of the scaffold may be straightened thereby compromising the desired curvature of the leaflets and functionality of the valve.
The second method is to culture the TEHV in a “closed configuration”. This means that the valve leaflets are attached to each other, which prevents shortening of the leaflets due to the internal tension that builds up in the leaflets during culture. However, it does not prevent ‘straightening’ or ‘flattening’ of the leaflets. In addition, it has been proven to be difficult to achieve a sufficiently large coaptation area between the leaflets in this way, which is crucial for in vivo functionality of the heart valve.
The present invention addresses these problems and provides devices, which allow for the maintenance and control of heart valve geometry during culture.